How to Look Up a GST/HST Number in Canada

Before you pay a supplier invoice that shows GST or HST, it is worth spending one minute confirming the number on it is real. The reason is simple: as a GST/HST registrant, you get to claim back the tax you paid on business purchases through input tax credits (ITCs) — but only if the supplier who charged you was actually registered with the CRA when they did it. If the number on the invoice turns out to be invalid or false, the CRA can deny your credit and you eat the full tax cost yourself. The CRA runs a free public registry for exactly this check, and this guide walks through it.

Step 1: Understand what you are checking

A GST/HST account number is 15 characters long: the 9-digit business number, then the two letters "RT," then a four-digit account reference — for example, 123456789RT0001. The "RT" part identifies it as a GST/HST account, and the four digits at the end distinguish branches or divisions of the same business.

The registry does not ask you to check all of that. It only needs the first nine digits, because the number by itself is not what you are really verifying — you are verifying the combination of the number, the business name, and the date. That is deliberate: the registry matches the name against the CRA's records, and the name to enter is the supplier's legal, operating or trading name as displayed on the invoice or on a sign at the place of business. If the name you type is spelled differently from how the CRA recorded it, the search fails — and a mismatched name is one of the regular reasons ITC claims get denied.

The third input is the date, and it matters more than most people expect. Registrations are not permanent: they can be cancelled, revoked, or given an end date. The registry lets you enter the date of the transaction so it confirms the supplier was registered that day, not just at some point. So pull these three things from the invoice before you start: the nine digits, the supplier's name as it appears on the invoice, and the invoice or transaction date.

Step 2: Open the CRA's GST/HST Registry

The registry lives on canada.ca under the CRA's e-services section, at the Confirming a GST/HST account number page. It is free and needs no login. The first page presents the terms and conditions for using the service — read them and accept to proceed. This is the only step that trips people up, and only because they do not expect a government search to have a terms screen at all.

One thing to be careful about: there is also a separate Confirming a simplified GST/HST account number registry, which is for digital-economy businesses registered under the simplified GST/HST rules (cross-border digital products, platform-based short-term accommodation). If you are checking a normal Canadian supplier's invoice, you want the standard GST/HST registry, not the simplified one. The simplified registry even points to the standard one for regular businesses, so if you land there, follow the pointer.

Step 3: Enter the three details and read the result

On the search form, enter the first nine digits of the account number — not the full 15-character version. Do not type the "RT" or the four digits after it; entries with the prefix fail. Then enter the supplier's business name as it appears on the invoice, and the transaction date, and search.

A match tells you the account was valid for that business on that date: the supplier could legitimately charge GST/HST on the invoice in your hand, and your input tax credit claim has its evidence. Print or save a screenshot of the confirmation page and file it with the invoice. Under the Excise Tax Act, registrants must have "sufficient evidence" before claiming input tax credits, and a dated screenshot from the official registry is the most direct evidence you can produce. Keep it for the same retention period as the rest of your tax records.

A "not registered" or no-match result means the number, name, and date did not line up. Before you assume anything about the supplier, work through the three boring explanations first, because they are the usual cause: a typo in the nine digits, a business name typed differently from how the CRA recorded it, or a transaction date that falls outside the registration period. Try the name exactly as it appears on the invoice first — the registry accepts the legal, operating or trading name — and if that still does not match, ask the supplier for the exact name they gave the CRA and re-run the search. If it still does not match and you believe the supplier is registered, call the CRA's Business Enquiries line at 1-800-959-5525 rather than guessing.

Step 4: Know when the check matters most

For an ordinary small invoice, the lookup is a one-minute habit. There are situations where skipping it can get expensive.

The big one is any purchase on which you will claim an input tax credit. The Input Tax Credit Information (GST/HST) Regulations set the invoice requirements: for purchases of $30 to $149.99 the invoice must show the supplier's GST/HST registration number, and for purchases of $150 or more it must show that plus your name, the payment terms, and a description of the supply. The CRA expects you to make sure the GST/HST you claim back was charged by someone actually registered — its receipts-and-invoices guidance points registrants to this exact registry "to make sure that your ITC claims only include GST/HST charged by someone who is registered for GST/HST." If the number is invalid or false, the claim is denied, and you pay the tax twice: once to the supplier, and again when the credit is taken away.

It also matters when the number itself looks odd. A supplier who cannot or will not provide a GST/HST number, a number with the wrong format, or a number that looks recycled from another invoice are all worth the phone call to the CRA. And re-check existing suppliers at least once a year: a registration that was valid when you onboarded them can be cancelled later, and ITCs claimed on later invoices are what an audit will look at. For purchases in the thousands, verify again before you pay even if you checked before.

What "not registered" does not mean is that the supplier is a criminal. Plenty of legitimate small businesses are not required to register — a supplier under the small-supplier threshold has no GST/HST number to give you, and they simply should not be charging you GST/HST either. The question the registry answers is narrower than "is this business legitimate": it is "can I safely claim the tax on this invoice back."

Step 5: If you cannot use the online tool, call the CRA

The registry is the fast route, but the CRA also confirms registration by phone. If a search keeps failing, if the supplier never gave you a number, or if you would rather have verbal or written confirmation, call Business Enquiries at 1-800-959-5525. The CRA's own guidance lists this line for confirming whether a company is registered.

There is a Quebec exception worth knowing. The CRA registry covers the federal GST/HST only. Quebec's sales tax — the QST — runs on a separate registration system, and you verify a Quebec supplier's QST number through Revenu Québec's online validation tool, not the CRA. Do not use the federal registry for a Quebec supplier's QST number; the two systems are completely separate, and the federal tool will give you nothing useful.

Confirm a GST/HST account number

People search for this check under a few names. A GST lookup, a CRA HST number lookup, and a GST/HST search are all the same job: confirm a GST/HST account number in the CRA's GST/HST Registry before you rely on it. The steps below pull the process into one place.

Check the format first. A GST/HST account number has three parts. The first part is the nine-digit business number, the root number the CRA gives a business. The second part is the program account identifier, RT, which marks the account as a GST/HST account. Payroll accounts use RP and corporation income tax accounts use RC instead. The third part is a four-digit reference number, most often 0001 for a first GST/HST account. Put together, a valid GST/HST number looks like 123456789RT0001. If the number on an invoice is much shorter, has no RT in it, or mixes the parts up, treat that as a prompt to verify, not as proof anything is wrong. Suppliers print the number in different layouts, with and without spaces.

Then run the registry search. Open the CRA's page for confirming a GST/HST account number, accept the terms, and enter three things: the first nine digits of the number only, the supplier's business name as it appears on the invoice, and the date of the transaction from the invoice. Leave the RT and the four-digit reference out of the search box. The registry checks the combination, not the number alone, and it answers for the date you entered. A confirmation means the account was registered to that business on that date.

When a number does not validate, work through the plain causes first. Most failed searches come down to one of four things:

1. A digit was copied wrong from the invoice. Re-read the nine digits and try again.
2. The name does not match the CRA's record. Try the name exactly as it appears on the invoice first — the registry accepts the legal, operating or trading name. If that still fails, ask the supplier for the exact name they gave the CRA and re-run the search.
3. The date falls outside the registration. An account can start after an early invoice or be cancelled before a later one. Check the transaction date against when the supplier says the account was active.
4. The supplier is not registered at all. A small supplier under the $30,000 threshold has no GST/HST account and should not be charging the tax.

If a careful re-check still fails, ask the supplier to confirm their registration details in writing. You can also call CRA Business Enquiries at 1-800-959-5525 and ask the CRA to confirm whether the business is registered. Hold off on claiming input tax credits for that invoice until the number checks out. The CRA can deny a credit claimed on an invalid number, and a short delay costs less than a denied claim. Keep the registry result, or a note of the phone call, with the invoice either way.

Making it a habit

The practical routine most bookkeepers follow is short: verify every new Canadian supplier before the first payment goes out, save the screenshot with the invoice, and re-verify the supplier list once a year. Fold it into vendor onboarding rather than treating it as a separate task, because a check that lives in your invoice-approval workflow is one that actually gets done. The registry is free, takes a minute, and is the one piece of due diligence the CRA itself built for you.

Related guides

• How to Register for GST/HST in Canada, the registration side of this process: the $30,000 threshold, the account format, and what changes once you are registered.
• Do You Need a GST Number as a Sole Proprietor in Canada?, the decision guide for the other side of the counter — when a supplier does and does not need a number at all.
• How to Register a Sole Proprietorship and GST/HST in Canada, for starting a business with its own BN and its own "RT" account — and its own invoices worth verifying.

Sources

• CRA — Confirming a GST/HST account number (Canada.ca) — the registry itself: free, first nine digits only, the supplier's legal, operating or trading name, and the transaction date; print the Search Details screen as proof for input tax credit claims.
• CRA — Terms and conditions of use, GST/HST Registry (Canada.ca) — the terms screen the registry presents before the search; registry information is as up to date as CRA records.
• CRA — Confirming a simplified GST/HST account number (Canada.ca) — the separate registry for digital-economy businesses (cross-border digital products and services, platform-based short-term accommodation); the registered-business list was updated November 3, 2026.
• CRA — Receipts and invoices (Canada.ca) — invoice requirements for GST/HST registrants and the pointer to the registry so input tax credit claims include only tax charged by someone registered for GST/HST.
• CRA — GST/HST for businesses (Canada.ca) — the CRA's GST/HST hub page, including the "Confirm a GST/HST number" service.
• Revenu Québec — Validate a QST Registration Number (entreprises.revenuquebec.ca) — the QST number verification service. Note: Revenu Québec moved this service; the old www.revenuquebec.ca/verify-a-qst-registration-number/ address returns "Page not found" as of November 9, 2026, and this entreprises.revenuquebec.ca address is the working service.